MOCK - Tell us what strange gear you've installed ROCK on!

(Chris) #144

I’m putting a ROCK in a KVM VM for testing purposes (the testing is in another thread). Hence the info in this thread is quite interesting.

On a note related to Wizardofoz’s post showing his A/B testing setup, this is how I A/B DACs:

The Mackie BigKnob Passive has two sets of balanced source and two sets of balanced monitor (TRS) jacks, plus headphone.

  • Passive
  • Volume (down to -100dB)
  • Stereo / Mono
  • Mute
  • Dimm
  • No clicks whatsoever (!) switching source and/or monitor

So, if someone pushes the source select, and you listen and have your eyes closed, you hear nothing except the difference between the two sources. And if you group those in Roon and then match their volumes, you have a fully blind A/B test.

Seen in the picture are an RPI 3 B+ with a HifiBerry DAC+ Pro XLR (balanced) and an ifi iDAC 2 (unbalanced), which I am comparing trying to decide which I like best. :brain:


(Chris) #145

What does the switcher do to the sound, perhaps you ask?
Not much:

Frequency Response
0 dBu Input: ±1 dB, 10 Hz – 30 kHz
Distortion (THD+N)
0 dBu Input @1 kHz: <0.005 %
Crosstalk (20 Hz – 20 kHz)
0 dBu Input @1 kHz: <–85 dB
Muted: –100 dB
Signal-To-Noise Ratio
A–weighted: <–100 dB

For A/B purposes, I guess you could say it doesn’t even have to have such great specs, as long as the sources are both affected the same you can make a comparison. Of course it helps that the switcher is as transparent as possible, so you can hear the most of your sources.

When I am not comparing DACs, I connect my amps directly to whatever unit I’m using, so the BigKnob is not in the chain all the time.

However, as stated, I find it not audible (however, and there is the joke; I’d have to A/B with and without the switcher to state that objectively, right?) :wink:


(Chris) #146


here then a post detailing a ROCK running in a Linux KVM VM on a CentOS 7.6 Server.

The VM has 2GB and 2 vCPUs, a SATA disk (using a 20GB qcow3 disk image), because sadly VirtIO disk drivers are not included in the ROCK image, but nicely enough a VirtIO network card worked fine.

ROCK says Roon Database has 91% of 16 GB available with about 11,000 Songs indexed.

Performance is fine, and seems to be the same as on a Roon core running in a Windows 10 VM, and same as a Roon core running natively on the CentOS Server.

Two disadvantages of ROCK seem to be a) doesn’t run extensions b) is fixed to a UTC time zone, causing Squeezeboxen to show UTC time.


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Is there a known-safe motherboard for a ROCK machine, if a NUC isn't quite working out?
(DWPress) #147

First Post, still in my trial period but will be signing up for a year. Had the core running on my 2015 MBP serving several zones in 3 buildings on my local network. Wanting to separate the core and processing from my work computer I decided to try the ROCK install on some pretty old hardware.

It’s an ancient 2007 Aopen DE965-HG with 4GB RAM and a T7250 C2D processor and a 120GB SSD. Loaded up the disk image onto a usb key with Etcher and bam! Perfect install first round, it updated it’s OS, loaded the ffmpeg codex no problem, transferred my core backup to the Aopen and it’s in the process of assimilating all the music as I type. I’ve already tried different zones like my AppleTV (3rd gen), Airport Express (old G variant), iPhone and MBP running 3 of them at a time and this is while the ROCK is still trying to index everything. Yes, the fan is running full tilt right now - we’ll see how it goes after the indexing is complete and I can probably mod it and replace the fan with a giant heatsink. Right now it’s streaming to the Roon app on my MBP and being output into a virtual soundcard - Sonarworks 4 Systemwide.

I plan to use Roon convolution to replace my MiniDSP 4x10 for active XO and room correction on my 3.3 (3 way speakers + 3 subs for even distribution) but haven’t gotten as far as firing up REW and rePhase yet to make filters. I’ll update here once I get that figured out and report how this old tech works for that task. I figure despite it’s age it’s already more powerful than a MiniDSP SHARK platform.

These things go for as little as $30.00 on eBay BTW…

(Henry) #148

I think if this is used purely to serve Roon you may be OK but if you try any demanding DSP it will probably run out of steam. Definitely worth doing though.

(DWPress) #149

Well it all worked just fine for the past 5 days to serve Roon to everything but I’ve decided to run it as a Linux host on a new HD so I could utilize some extensions but I have the ROCK HD set aside and can swap it out to experiment with later. As of now my core is back on the MBP until I sort out the Roon Linux install. I’ve yet to try my hand at any convolution filters but when I do I’ll report back how the ROCK install does with them on this machine.

(DWPress) #150

Eighteen day update. I tried an Ubuntu set up but settled on Win7 32 as a server so this machine could also do double duty as a Plex server for video. It’s actually got a decent optical drive so I’m using it as a ripping machine as well with Exact Audio Copy app directly to the networked media drive as well as a local USB one. I run it headless and just screen share from my Macbook Pro when I need access or ripping CDs.

I still haven’t used it for XO convolution but have set up some filters via REW and Rephase using 262k taps, bit depth conv, volume leveling, headroom mgt, sample rate conv, and para EQ all going and I can see where a more powerful processor may be in order for trying the XO bit as the processing speed is around 10x. I’ve picked up a cheap USB 8 channel sound card so I’ll give it a try anyway and report back one more time but will probably move things over to a 2012 Mac Mini for the final job.

For basic server functions and even the extreme bit of DSP I’m using right now one of these ancient little boxes works just fine. Not a single stutter in 18 days.

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